Update of /project/climacs/cvsroot/climacs/Doc In directory common-lisp.net:/tmp/cvs-serv24900/Doc

Modified Files: climacs-internals.texi Log Message: Added section on incremental parsing.

Date: Tue Mar 1 05:56:29 2005 Author: rstrandh

Index: climacs/Doc/climacs-internals.texi diff -u climacs/Doc/climacs-internals.texi:1.14 climacs/Doc/climacs-internals.texi:1.15 --- climacs/Doc/climacs-internals.texi:1.14 Sun Feb 27 20:13:47 2005 +++ climacs/Doc/climacs-internals.texi Tue Mar 1 05:56:27 2005 @@ -716,6 +716,91 @@ present, and it should be exploitable by several, potentially totally different, display units.

+@section Incremental parsing framework + +@subsection Earley parser + +Climacs contains an incremental parser that uses the Earley +algorithm. This algorithm accepts the full set of context-free +grammars, allowing greater freedom for the developer to define natural +grammars without having to think about restrictions such as LL(k) or +LALR(k). + +Beware, though, that the Earley algorithm can be quite inefficient if +the grammar is sufficiently complicated, in particular if the grammar +is ambiguous. + +@subsection Specifying a grammar + +An incremental parser is created from a grammar. + +@deffn {Macro} {grammar} &body rules + +Create a grammar object from a set of rules +@end deffn + +@deffn {Rule} {} symbol -> (&rest arguments) &optional body + +Each rule is a list of this form. +@end deffn + +@noindent +Here @var{symbol} is the target symbol of the rule, and should be the name of +a CLOS class. + +@deffn {Rule argument} {} (var type test) + +The most general form of a rule argument. +@end deffn + +@noindent +Here @var{var} is the name of a lexical variable. The scope of the +variable contains the test, all the following arguments and the body +of the rule. The @var{type} is a Common Lisp type specification. The +rule applies only of the @var{type} of the object contain in var is of +that type. The @var{test} contains arbitrary Common Lisp code for +additional checks as to the applicability of the rule. + +@deffn {Rule argument} {} (var type) + +Abbreviated form of a rule argument. +@end deffn + +@noindent +Here, @var{type} must be a symbol typically the name of a CLOS class. +This form is an abbreviation for @code{(@var{var} @var{type} t)}. + +@deffn {Rule argument} {} (var test) + +Abbreviated form of a rule argument. +@end deffn + +@noindent +Here, @var{test} must not be a symbol. This form is an abbreviation +of @code{(@var{var} @var{var} @var{test})}, i.e., the name of the +variable is also the name of a type, typically a CLOS class. + +@deffn {Rule argument} {} var + +Abbreviated form of a rule argument. +@end deffn + +@noindent +This form is an abbreviation of @code{(@var{var} @var{var} t)}. + +The @var{body} of a rule, if present, contains an expression that should +have an instance (not necessarily direct) of the class named by the +symbol (the left-hand-side) of the rule. It is important that this +restriction be respected, since the Earley algorithm will not work +otherwise. + +If the @var{body} is absent, it is the same as if a body of the form +@code{(make-instance '@var{symbol})} had been given. + +The body can also be a sequence of forms, the first one of which +must be a symbol. These forms typically contain initargs, and will be +passed as additional arguments to @code{(make-instance '@var{symbol})}. + @section Common Lisp syntax

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